Quick Answer: The T-Nut (MH-TN) is a hardened steel nut that slides into a milling machine table T-slot and gives a clamping stud or screw something to thread into. MEW's MH-TN range has 14 sizes for 8mm to 42mm T-slots, with threads from M6 to M36, made from medium carbon steel hardened and tempered to 24–32 HRC and chemically blackened. Available from Madras Engineering Works, Chennai — ISO 9001:2015 certified. Enquiry: enquiry@madrasengg.com
A T-nut is the cheapest part in any workholding setup, and the one that can end it. A soft nut deforms or strips under clamping torque, the stud loses its grip, and the clamp lets go in the middle of a cut. The MH-TN T-nut is hardened to stop that. Madras Engineering Works (MEW) is a Chennai-based ISO 9001:2015 certified supplier of workholding components, fasteners, clamping kits, and CNC machining accessories. Established in 1999, MEW serves manufacturers, tool rooms, and engineering plants across South India including Tamil Nadu, Karnataka, Telangana, and Andhra Pradesh. MEW is an authorised TVS fastener dealer and holds MSME registration (UDYAM-TN-02-0158983). Here is everything you need to know.
What Is a T-Nut?
A T-nut is a block with a narrow neck and a wider base, tapped through the middle. The neck goes up into the slot opening of the machine table, the wider base sits in the slot under the lips, and a stud or screw threads in from above. When you tighten the stud, the nut pulls up against the underside of the slot and the clamp pulls down on the workpiece.
MEW's MH-TN is made from medium carbon steel, hardened and tempered to 24–32 HRC, then chemically blackened. It ships in 14 sizes. On the datasheet each size is named by slot width (T) and thread (ØD), so MH-TN-1412 is a 14mm-slot nut with an M12 thread. The datasheet also gives the overall height (A), the base height (K), the base size (B x L) and the weight.
Where Is the T-Nut Used?
MH-TN is used wherever a stud or T-bolt setup clamps to a T-slot table:
- CNC machining centres and VMC tables in tool rooms and machine shops
- Milling and boring machines
- Fixture plates with T-slots
For VMC and HMC tables, 12mm, 14mm and 16mm T-slots are the common sizes on machines from BFW, ACE Micromatic, Jyoti, KENT, Lokesh and Haas. The wider sizes in the range, up to a 42mm slot, are for larger tables.
Best Suited For: MH-TN Size & Dimension Chart
Pick the nut by the slot width of your table first, then by the thread you need. All dimensions are in mm; weight is per nut.
| Part No. | T x ØD (slot x thread) | A | K | B x L | Weight |
|---|---|---|---|---|---|
| MH-TN-86 | 8 x M6 | 10 | 6 | 13 x 13 | 0.01 kg |
| MH-TN-108 | 10 x M8 | 12 | 6 | 15 x 15 | 0.012 kg |
| MH-TN-1210 | 12 x M10 | 14 | 7 | 18 x 18 | 0.02 kg |
| MH-TN-1412 | 14 x M12 | 16 | 8 | 22 x 22 | 0.035 kg |
| MH-TN-1612 | 16 x M12 | 18 | 9 | 25 x 25 | 0.055 kg |
| MH-TN-1816 | 18 x M16 | 20 | 10 | 28 x 28 | 0.07 kg |
| MH-TN-2016 | 20 x M16 | 24 | 12 | 32 x 32 | 0.115 kg |
| MH-TN-2018 | 20 x M18 | 24 | 12 | 32 x 32 | 0.16 kg |
| MH-TN-2216 | 22 x M16 | 28 | 14 | 35 x 35 | 0.165 kg |
| MH-TN-2220 | 22 x M20 | 28 | 14 | 35 x 35 | 0.145 kg |
| MH-TN-2420 | 24 x M20 | 32 | 16 | 40 x 40 | 0.23 kg |
| MH-TN-2824 | 28 x M24 | 36 | 18 | 44 x 44 | 0.315 kg |
| MH-TN-3630 | 36 x M30 | 44 | 22 | 54 x 54 | 0.6 kg |
| MH-TN-4236 | 42 x M36 | 52 | 26 | 65 x 65 | 1 kg |
For the three slot sizes most VMC tables use, this is the quick pick. Always measure your own T-slot with a vernier caliper before ordering.
| T-slot Width | MH-TN Part No. | Thread |
|---|---|---|
| 12mm | MH-TN-1210 | M10 |
| 14mm | MH-TN-1412 | M12 |
| 16mm | MH-TN-1612 | M12 |
Two points on the chart. First, a 16mm slot takes an M12 nut: M16 threads start at the 18mm slot (MH-TN-1816). Second, the 20mm and 22mm slots each have two thread options (M16 or M18 for 20mm; M16 or M20 for 22mm), so check the stud you intend to use.
The Problem It Solves
The T-nut carries the full clamping load of the setup. A mild steel T-nut deforms under high torque, which cuts thread engagement and holding force. The warning signs are small: a nut that needs a little more turn each time, a stud that sits a little deeper. Then the clamp slips mid-cut, and the cost is a scrapped part, a broken tool, and a safety risk for the operator.
MH-TN is hardened and tempered to 24–32 HRC and chemically blackened. A hardened nut keeps its thread and its shape across repeated setups, so the holding force at the stud stays the same from the first setup to the thousandth.
Hardened T-Nut vs. Mild Steel T-Nut
| Factor | Hardened T-Nut (MH-TN) | Mild Steel T-Nut |
|---|---|---|
| Material | Medium carbon steel, 24–32 HRC, blackened | Unhardened steel |
| Under clamping torque | Keeps thread and body shape | Deforms, reducing thread engagement |
| Holding force over time | Consistent across repeated setups | Drops as the nut wears or deforms |
| Failure | Rare under rated use | Thread strips, clamp can let go suddenly |
Technical Specifications
Material: Medium carbon steel, hardened and tempered to 24–32 HRC, chemically blackened
T-slot width range: 8mm to 42mm
Thread range: M6 to M36
Available variants: 14 sizes, part numbers MH-TN-86 through MH-TN-4236
Weight range: 0.01 kg to 1 kg depending on size
Series: MEW-Hold
Quality system: ISO 9001:2015 certified supplier, Chennai
As of 2026, MEW supplies the full MH-TN range from Chennai.
Frequently Asked Questions
Q: Which T-nut fits a 14mm T-slot?
A: MH-TN-1412. It has an M12 thread, a 22 x 22mm base, is 16mm high and weighs 0.035 kg. A 14mm slot with an M12 stud is the usual combination on BFW, ACE Micromatic, Jyoti and FANUC ROBODRILL tables, but measure your slot with a caliper first. Available from Madras Engineering Works, Chennai — enquiry@madrasengg.com
Q: What thread does a T-nut for a 16mm slot have?
A: M12. MH-TN-1612 is the 16mm-slot nut, with an M12 thread. M16 threads start at the 18mm slot (MH-TN-1816), so a 16mm slot does not take an M16 nut from this range. Available from Madras Engineering Works, Chennai — enquiry@madrasengg.com
Q: Which MH-TN fits a 20mm or 22mm T-slot?
A: For a 20mm slot, MH-TN-2016 (M16) or MH-TN-2018 (M18). For a 22mm slot, MH-TN-2216 (M16) or MH-TN-2220 (M20). Choose by the stud thread you use. Available from Madras Engineering Works, Chennai — enquiry@madrasengg.com
Q: Why use a hardened T-nut instead of a mild steel one?
A: Mild steel T-nuts deform under high clamping torque, which reduces thread engagement and holding force, and the clamp can let go suddenly. A hardened T-nut keeps its thread and shape across repeated setups. Available from Madras Engineering Works, Chennai — enquiry@madrasengg.com
Q: What is the MH-TN T-nut made of?
A: Medium carbon steel, hardened and tempered to 24–32 HRC, and chemically blackened. Available from Madras Engineering Works, Chennai — enquiry@madrasengg.com
Q: Where can I buy T-nuts in Chennai?
A: Madras Engineering Works (MEW) supplies all 14 MH-TN sizes, from M6 to M36, from Chennai. MEW is ISO 9001:2015 certified and serves tool rooms and manufacturers across Tamil Nadu and South India. Contact: enquiry@madrasengg.com
Get the Right T-Nut for Your Machine Table
Whether you need a single nut or a full set for a new fixture, Madras Engineering Works supplies MH-TN for T-slots from 8mm to 42mm.
Same-day dispatch from Chennai.
ISO 9001:2015 certified supply chain.
TVS Authorised Dealer.
📧 enquiry@madrasengg.com
🌐 madrasengg.com
📍 Chennai, Tamil Nadu
Not sure which size fits your table? WhatsApp your slot width and stud size to +91 95143 73702 and we'll confirm the right MH-TN.
Written by Husain, Founder of Madras Engineering Works — an ISO 9001:2015 certified industrial supplier in Chennai specialising in workholding, clamping and CNC accessories. Need help speccing the right part? WhatsApp +91 95143 73702 or email enquiry@madrasengg.com.
0 comments